Conveyors for feeding and mixing bulk materials are known.
In known screw conveyors with a single feed screw, the open trough has a maximum inside width which corresponds approximately to the diameter of the screw and the base of the trough is circular over half the circumference of the screw. The radius of curvature of the circular base is about equal to the radius of the screw.
In the known screw conveyor with two equal and parallel feed and mixing screws located in a common trough with interfitting of the flights, the interior width of the trough corresponds approximately to the center-to-center spacing of the screws from each other plus twice the radius of one of the screws. The trough base has two circular regions spaced apart and disposed one beside the other and with radii of curvature is almost equal to the screw radius.
To obtain a sufficiently thorough mixing and, if necessary, a uniform wetting of the mixed material, the screw conveyor has a comparatively great length which requires a comparatively large expense in material and work time. At the same time the weight and the spatial requirements of the apparatus are considerable.